Ultra-Processed Food Linked to Men’s Colorectal Cancer Risk

Men who take in high rates of ultra-processed foods are at 29% higher risk for developing colorectal cancer than men who eat much smaller amounts, research finds.

The study didn’t find the same relationship in women.

Colorectal carcinoma is the third-most common type of cancer.

“We started out thinking that colorectal cancer could be the cancer most impacted by diet compared to other cancer types,” says Lu Wang, a postdoctoral fellow at the Friedman School of Nutrition Science and Policy at Tufts University, and lead author of the study in The BMJ.

“Processed meats, most of which fall into the category of ultra-processed foods, are a strong risk factor for colorectal cancer. The high levels of added sugars in ultra-processed food and the low fiber content are a risk factor for colorectal carcinoma .”

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The study analyzed responses from over 200,000 participants–159,907 women and 46,341 men–across three large prospective studies which assessed dietary intake and took place over more than 25 years. Researchers provided each participant with a food frequency questionnaire every four years and asked about the frequency of consumption of roughly 130 foods.

Researchers classified the participants’ consumption of ultra-processed food into quintiles. These range in value from low to high. The highest quintile was identified to be at greatest risk of developing colorectal carcinoma. The study found a strong link between colorectal and distal colon cancers in men. However, it did not show an increased risk in women who consume more processed foods.

Meat, Cheese, and Fish Cakes

The analyses showed differences in how men and women consume processed foods, and their potential cancer risks. Out of the 206,000 participants followed for more than 25 years, the research team documented 1,294 cases of colorectal cancer among men, and 1,922 cases among women.

The strongest link between colorectal carcinoma and processed foods in men was found to be from meats, fish, and poultry-based ready-to-eat food products.

” These products contain some processed meats such as bacon, sausages and fish cakes. Wang states that this is in line with our hypothesis.

The team also found higher consumption of sugar-sweetened beverages, like soda, fruit-based beverages, and sugary milk-based beverages, is associated with an increased risk of colorectal cancer in men. Not all processed foods can be equally dangerous in terms of colorectal risk.

” We found an inverted association between yogurt, ultra-processed dairy products and colorectal carcinoma risk in women,” said Fang Fang Zhang (co-senior author), a nutrition epidemiologist at Friedman School and interim chair for the division of data science and nutrition epidemiology.

Overall there wasn’t a connection between colorectal risk in women and ultra-processed foods. There is a possibility that women may be exposed to a different type of ultra-processed food than men.

“Foods like yogurt can potentially counteract the harmful impacts of other types of ultra-processed foods in women,” Zhang says.

“More research is needed to establish if there’s a sex difference between the associations or if the null results in women in this investigation were due to luck or other uncontrolled confounding variables in women,” Mingyang Song (assistant professor of clinical epidemiology, nutrition, Harvard University T.H.). The study was co-authored by Mingyang Song, assistant professor of clinical epidemiology and nutrition at Harvard University T.H. Chan School of Public Health.

Although ultra-processed food is often associated with low diet quality, other factors could also play a role in increasing the chance of getting colorectal carcinoma.

Zhang notes that food additives could alter gut microbiota , and promote inflammation. Also, contaminants formed in food processing or migrated out of food packaging might all contribute to cancer development.

Decades of Data

With more than a 90% follow-up rate from each of the three studies, the research team had ample data to process and review.

“Cancer can take years, or even decades, to develop. Our epidemiological studies have demonstrated the possible latency effect–it can take years to notice an effect on certain exposures on cancer risk,” Song says. This long process makes it important to be able to evaluate the risk of developing cancer .”

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The studies were:

• The Nurses’ Health Study (1986-2014): 121,700 registered female nurses between the ages of 30 and 55
• The Nurses’ Health Study II (1991-2015): 116,429 female nurses between the ages of 25 and 42
• The Health Professional Follow-up Study (1986-2014): 51,529 male health professionals between the ages of 40 and 75.

After an exclusionary process for past diagnoses or incomplete surveys, the researchers were left with prospective data from 159,907 women from both NHS studies and 46,341 men.

The team considered potential confounding factors like race, family history, cancer history, endoscopy history, daily physical activity, smoking, alcohol consumption, caloric intake and regular aspirin usage.

Zhang knows that these participants all work in healthcare. This means the results for them may differ from those for the general population. Participants may also be more likely to be healthier and less inclined towards processed foods. Data may be biased due to changes in processing over the last two decades.

“We are trying to compare the consumption of higher and lower quantities within this population,” Zhang said. These comparisons are valid .”

Reducing Colorectal Cancer Burden

Wang and Zhang previously published a study that identified a trend in increased ultra-processed food consumption in US children and adolescents. These studies highlight the possibility that ultra-processed food may have a significant impact on many groups.

” Some of this dependence can be attributed to food accessibility and convenience,” Zhang says. Zhang is also part of the Tufts International for Global Obesity research.

“While chemically processing food can extend shelf life, many processed foods have lower nutritional value than those that are not. We need to make consumers aware of the risks associated with consuming unhealthy foods in quantity and make the healthier options easier to choose instead.”

Wang understands that changes won’t occur overnight and hopes this research, along with others, will help to change dietary recommendations and regulations.

“Long term change requires a multi-step approach,” Wang says. Researchers continue to study how nutrition-related policies and dietary recommendations can help improve overall health, as well as the effects of lifestyle changes and other healthy habits on cancer risk. We will continue to research the relationship between diet and cancer, as well the possible interventions that could improve the outcomes.

The work was funded by the National Institutes of Health’s National Institute on Minority Health and Health Disparities and the National Cancer Institute.

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This article was originally published by Tufts University. Republished via Futurity.org under Creative Commons License 4.0.